The invention resides in an arrangement for handling the fuel in a common-rail fuel injection system of an internal combustion engine, having a fuel supply line with a low pressure pump and a first fuel filter arranged in the fuel supply line downstream of the low-pressure pump and a high-pressure pump, arranged in the fuel line downstream of the first fuel filter for supplying high pressure fuel to a fuel injection rail of the internal combustion engine, as well as a bypass line, which includes a heat exchanger and a second filter for returning fuel into the fuel supply line upstream of the high-pressure pump.
A fuel circuit having a tank and a low-pressure pump connected via a fuel line is already known from U.S. Pat. No. 5,794,598. A fuel filter and then a high-pressure pump, which is connected to the internal combustion engine, are provided downstream of the low-pressure pump. A return line extends from the high-pressure pump and is connected back to the fuel line upstream or downstream of the fuel filter, the return line having a heat exchanger. The heat exchanger is designed as a fuel/air or fuel/coolant and coolant/air heat exchanger. An additional filter may also be arranged within the return line.
GB 2 292 184 describes on page 9, final paragraph, a return line (recirculation duct 334) for the injection rail. The document does not describe a bypass line for the injection rail causing the fuel to bypass the injection rail. The document also does not describe the use of a cooling circuit of an air-conditioning system or of an internal combustion engine.
EP 0 656 470 A also describes a return line but not a bypass line.
DE 199 63 229 A, contrary to the cooling device according to the invention, describes a device for heating fuel which is equipped with a return line.
It is the object of the present invention to provide a fuel supply circuit for a common rail injection system of an internal combustion engine in such a manner as to ensure simple and inexpensive cooling for the fuel.